Nearly two-and-a-half years have passed since Shin Hae-chul, one of the nation’s most famous pop musicians, died from a medical accident, but it seems unlikely his fans will soon know exactly where the responsibility lies.

In the first hearing of the appeals trial Thursday, Kang Se-hoon, the doctor who was convicted in a lower court on a charge of professional negligence resulting in death, pleaded not guilty. Prosecutors also indicted Kang for the misappropriation of business secrets and violation of medical law. The first trial found him not guilty on the latter two charges, however.

Kang is suspected of conducting a stomach surgery on Shin without the latter’s consent, accidentally puncturing his small intestine and pericardium and causing the peritonitis and blood poisoning, which killed the star singer in October 2014.

Shin reportedly complained of chest pain after undergoing intestinal surgery at Sky Hospital in southern Seoul and died of heart failure a few days later. Kang is also accused of failing to take proper measures after the singer complained of continued pain.

Prosecutors said Kang ignored the danger signs, such as abdominal swelling and a high white blood cell count. All Kang did was prescribing painkillers and telling him to put up with the pain, according to lawyers representing the victim's family.

Kang Se-hoon speaks at an appeals court Thursday, defending himself from a charge of professional negligence resulting in the death of musician Shin Hae-chul in 2014.

After Shin had died, Kang closed the hospital but opened a new hospital later and has continued his obesity metabolic surgery.

The Ministry of Health and Welfare, after receiving complaints about complications and other problems from other patients, has ordered Kang to discontinue the obesity metabolic surgery based on Provision 1, Article 59, of the Medical Law.

The first trial judges sentenced Kang to eight months in jail with a stay of execution for two years while maintaining Kang’s license. Both the prosecution and Kang appealed the ruling.

The prosecution has pointed out in the petition statement that there is a legal misunderstanding on the part of the judiciary regarding the charges of business secret leaks and violations of the medical law, and the penalty for the accidental homicide was too lenient, given the nature of the crime.

Kang's attorney struck back, saying, "Shin’s death is due to his failure to follow the doctor’s instruction on hospitalization, and so Kang does not deserve what happened to his patient.”

The judges also questioned Kang about the cardiac puncture, the cause of Shin's death.

Kang reiterated his advice – or instruction – for Shin to stay at the hospital and undergo checkups, which the latter did not follow.

Lawyers for Shin, however, stressed the late musician did not content to the stomach surgery in the first place, pointing out that there were two more victims, including an Australian, for similar reasons.

Experts said the legal battle would likely go on for some time, but the medical community will need to seriously consider drawing a clearer line between the rights of patients and their doctors, including how much can be excused under the doctors’ arbitrary and unproven surgical procedure in the name of bona fide intention.